As bonding members having excellent workability and a high reliability of adhesiveness, adhesive tapes are being used for fixing parts in various industrial fields of OA equipment, IT and home appliances, automobiles, and the like, temporarily fixing parts, labeling for displaying product information, and the like. In recent years, in view of protection of the global environment, in the various industrial fields of home appliances, automobiles, and the like, there has been an increased demand for used products to be recycled or reused. In order to recycle or reuse various products, it is necessary to perform an operation of peeling the adhesive tape used for fixing parts or labeling. However, because the adhesive tape can be placed anywhere on the product, implementing a simple removal step to reduce operational costs is desired.
As an easily dismantlable adhesive tape, for example, there is a disclosure regarding an adhesive member having two or more adhesive layers having different degrees of adhesive force (see Patent Document 1). The adhesive tape is an adhesive member which is bonded to an adherend through a weak adhesive layer in the adhesive member including adhesive layers having a superimposed structure. In this way, the adhesive tape firmly affixes to the adherend and is easily dismantled by using the weak adhesive layer as a peeling surface. However, the adhesive member has a problem that the production cost thereof becomes high since multiple adhesive layers are required as essential constituents. Furthermore, since the member is adhered to an adherend through a weak adhesive layer, there is a limit on increasing the adhesive force, and accordingly, it is difficult to use the adhesive member to firmly fix articles.
As another easily dismantlable adhesive composition, there is a disclosure regarding an adhesive composition containing aliphatic polyester (see Patent Document 2). According to the disclosure, when being dipped into warm water for a peeling operation, the adhesive composition can be easily peeled by hydrolysis-accelerating action of polycaprolactone. However, in order to be peeled off, the adhesive composition disclosed needs to be dipped in warm water. Therefore, when the size of a member to be dismantled is large, the cost of equipment increases, and the composition cannot be applied to parts for which water cannot be used, such as in the case of reusing electronic parts.
Furthermore, even when the adhesive force of an adhesive tape is greatly reduced at the time of dismantlement, if stick-slip occurs when the adhesive tape is peeled off from an adherend or when the adhesive layer is peeled off from a substrate, sometimes parts of various industrial products are broken when the products are recycled or reused, adhesive residues partially remain in the parts, or workability deteriorates when a large number of articles are dismantled.
Moreover, as an adhesive composition using an acrylic block copolymer, there is a disclosure regarding an adhesive composition containing a block copolymer which is obtained by producing an acrylic copolymer having a carboxyl precursor group (—COOt-butyl) in an acrylic polymer block and then substituting the carboxyl precursor group with a carboxyl group (see Patent Document 3). The adhesive composition has a step of producing an acrylic copolymer having a t-butyl group on the side chain, as the carboxyl precursor. However, the t-butyl group does not remain in the obtained adhesive composition, and the composition does not have dismantlability.